1. Field of the Invention
The present invention relates to a triangular to sine wave converter receiving a triangular wave to produce an output of a substantially sinusoidal waveform.
2. Description of the Related Art
As well known, a sinusoidal signal of an electronic apparatus is produced by a combination of an oscillator producing a reference frequency signal and a circuit waveform-shaping the received reference frequency to produce a sine wave.
A waveform-shaping circuit of a sine-wave generator generally employs a diode function generator. However, the diode function generator has a decisive drawback in producing a differential noise. FIG. 6 illustrates a prior-art sine-wave generator free from differential noise. The sine-wave generator of FIG. 6 comprises two four-input multipliers M.sub.1 and M.sub.2 receiving a reference frequency signal V.sub.i and produces a sinusoidal output V.sub.o by means of the following circuit transfer function: ##EQU1##
Factorizing the transfer function produces the following expression: ##EQU2## The denominators of the final expression comprise the imaginary number.
Since the prior-art sine-wave generator of FIG. 6 employs special operators and has a relatively complicated configuration of circuit, it is costly. In view of function, the transfer function of the sine-wave generator, which includes a numerator in the form of a cubic expression and a denominator in the form of a quadratic expression, is very disadvantageous in signal processing.